A case has been registered against Sonu Kumar (18) on the the complaint of the girl's parents and the principal of the inter-college, police said today.
S.O Kadrabad Satya Pal Singh said efforts were being made to nab the accused.
Sonu Kumar, a resident of Murliwala village, was a student of class XI but left the college last year after failing in the annual examination, Singh said.
On Friday, Kumar reached the inter-college with vermilion in his pocket and a rakhi in hand and entered the girl's classroom. "When the teacher tried to stop him, Kumar said he had come to get rakhi tied by his 'adopted sister' and instead applied sindoor (vermilion) on her forehead," the official said.